Alkyl , interconversion with acyl

Interconversion of Acyl (Meta Director) with Alkyl (Ortho, Para Director)... 

However, non-bridged calix[6]arene derivatives may also be chiral. It was possible to prepare two diastereomeric 1,2-dibenzyl ethers from /-butyl-calix[6]arenes with a syn and anti orientation of the ether residues. The free energy barrier for their mutual interconversion was found to be about 27 kcal mol". 160 This should be high enough to separate the enantiomers of the a/ift -isomer, which has effective C2 symmetry. The same should be true for another example of this type, a 1,2-p-nitrobenzoate with an anti-configuration161 and for 1,2,4-tri-O-alkyl or acyl derivatives.162... 

Taken together, the various reactions and interconversions of these manganese porphyrin complexes have allowed the examination of each step in the activation of molecular oxygen by the mechanism suggested for P-450. Detailed mechanistic studies of the 0-0 bond cleavage event in 29 by kinetics, substituent effects, and product analysis showed that the reaction proceeds via heterolysis to produce 27 when acid is present, whereas homolysis is predominant in the absence of acid but in the presence of hydroxide ion (95). Under basic conditions, homo-lytic cleavage of the 0-0 bond of 29 forms Mn (=0)TMP (28) and an acyl-oxyl radical. Thus, when an alkyl peroxy acid is employed, decarboxylation competes with electron transfer, as shown in Scheme IX, to afford a mixture of 27 and 28. Yuan and Bruice have proposed a similar heterolysis mechanism based on the kinetic analysis for the reaction of mCPBA with catalytic amounts ofMn TPP(/(W). 

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